MeeGo

Nokia's stock price has nearly doubled since hitting bottom last summer, but it's premature to call this a turnaround for the company that, until recently, was the world's largest cell phone maker. If anything, at least one analyst sees this as a selling opportunity.

Nokia once led the world in mobile handset sales. Now, even a billion-dollar boost from Microsoft may not be enough to save it. The markets have seen the Windows Phone-based Lumia 900 -- and sent the stock to an all-time low.

Nokia announced that it had chosen Stephen Elop to become its next CEO. But Nokia has seen its market share fall from 50% to 32% during the past three years, and Elop takes the job with virtually no experience in handsets, turnarounds, or meaningful innovation.